<ViewModels:MainViewModel 
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"       
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" xmlns:ViewModels="clr-namespace:GTasksPlus.ViewModels"
    xmlns:Model="clr-namespace:GTasksPlus.Model">
    <ViewModels:MainViewModel.Tasks>
        <Model:TaskListItem title ="test 1" id ="one"/>
        <Model:TaskListItem title ="test 2" id ="one"/>
        <Model:TaskListItem title ="test 3" id ="one"/>
        <Model:TaskListItem title ="test 4" id ="one"/>
    </ViewModels:MainViewModel.Tasks>
</ViewModels:MainViewModel>